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Few studies have documented the long-term oncological outcomes of favorable and unfavorable intermediate-risk (IR) prostate cancer patients treated via contemporary high-dose irradiation. We analyzed the ultimate clinical outcomes of such patients using the current risk sub-stratification schema.We included 693 patients with localized IR prostate cancer treated via low-dose-rate brachytherapy (LDR-BT) with or without external beam radiation (EBRT) and with or without androgen-deprivation therapy (ADT) in a single institution. Treatment outcomes (biochemical recurrence-free survival [BCRFS] and clinical progression-free survival [CPFS]) were compared according to the numbers of unfavorable findings.Out of the 693 IR patients, 292 (42.1%) exhibited favorable disease; the remaining 401 (57.9%) exhibited unfavorable disease. Compared with favorable IR status, unfavorable IR status was associated with shorter BCRFS and CPFS (p 0.001 and p 0.001, respectively). Patients with two to three unfavorable factors experienced the worst oncological outcomes (p 0.001 and p 0.001). Although patients with one or no unfavorable factors responded similarly to LDR-BT monotherapy, this treatment modality was insufficient for preventing biochemical and clinical progression in patients with multiple unfavorable findings.Long-term treatment outcomes indicate that patients with IR disease scheduled for LDR-BT should undergo multimodal irradiation if they exhibit two or more unfavorable factors at diagnosis.

To compare long-term outcomes of radical prostatectomy (RP) and low-dose-rate brachytherapy (LDR-BT) using propensity score-matched analysis in patients with clinically localized, intermediate-risk prostate cancer (PCa).Between October 2003 and March 2014, our institution treated 1241 patients with intermediate-risk PCa (RP: n = 531; LDR-BT: n = 710). Biochemical recurrence (BCR) was defined as prostate-specific antigen (PSA) levels of 0.2 ng/ml or greater for RP, and as PSA nadir plus 2 ng/ml or higher (Phoenix definition) for LDR-BT. We calculated propensity scores by multivariate logistic regression based on covariates that included age, pretreatment PSA, biopsy Gleason grade, the percentage of positive biopsy cores (PPBC), and clinical T stage.Median follow-up was 108 months for RP and 99 months for LDR-BT. After propensity score adjustment, a total of 642 (321 each) patients remained for further analysis. Kaplan-Meier curves showed no statistically significant difference in overall survival (OS) (p = 0.99). LDR-BT was associated with improved BCR-free survival and salvage therapy-free survival compared to RP (p 0.001), and RP was associated with improved metastasis-free survival (MFS, p 0.001).BCR cannot be a surrogate for survival comparison, primarily due to differences between treatment modalities in how this term was defined post-therapy. Long-term follow-up showed that RP was associated with lower MFS in intermediate-risk PCa. However, this has not yet translated into superior OS.

The prognostic significance of PSA bounce following definitive radiation therapy remains controversial. To develop a sense of current opinion in this area, we performed a systematic search of the literature based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses. In January 2021, we systematically searched PubMed, the Cochrane library, and Scopus for studies that compared patients who had localized prostate cancer with or without PSA bounce after definitive radiation therapy. Our objective was to evaluate the association of PSA bounce with biochemical recurrence-free survival, metastatic-free survival, cancer-specific survival, and overall survival, using multivariate Cox regression analysis. A total of 8881 patients in 10 studies matched the selection criteria for the systematic review and meta-analysis. The number of patients with PSA bounce accounted for 2706 of all 8881 patients (30.5%). PSA bounce was associated with better biochemical recurrence-free survival after definitive radiation therapy (pooled HR: 0.62, 95% CI: 0.54–0.71). Subgroup analyses also showed that PSA bounce was independently associated with decreased risk for biochemical recurrence-free survival in prostate cancer patients treated with low dose rate brachytherapy alone (pooled HR: 0.38, 95% CI: 0.27–0.55) and external beam radiotherapy alone (pooled HR: 0.71, 95% CI: 0.57–0.87). This meta-analysis indicated that PSA bounce after definitive radiation therapy is related to improved outcome in terms of biochemical failure in prostate cancer patients.

The design, synthesis, X-ray structural, and biological evaluation of a series of highly potent HIV-1 protease inhibitors are reported herein. These inhibitors incorporated novel cyclohexane-fused tricyclic bis-tetrahydrofuran as P2 ligands in combination with a variety of P1 and P2’-ligands. The inhibitor with a difluoromethylphenyl P1 ligand and a cyclopropylaminobenzothiazole P2’ ligand exhibited the most potent antiviral activity. Also, it maintained potent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The corresponding inhibitor with an enantiomeric ligand was significantly less potent in these antiviral assays. The new P2 ligands were synthesized in optically active form using enzymatic desymmetrization of meso-diols as the key step. To obtain molecular insight, two high resolution X-ray structures of inhibitor-bound HIV-1 protease were determined and structural analyses have been highlighted.

Objective: To explore radiation oncologists’ attitudes and practice patterns of radiotherapy for hormone-naïve prostate cancer with bone metastases in Japan. Methods: An internet-based survey was distributed to board-certified radiation oncologists of the Japanese Society of Radiation Oncology. Three hypothetical cases were assumed: hormone-naïve prostate cancer with single, three or multiple non-symptomatic bone metastases. The respondents described their attitude regarding such cases, treatment methods and the radiotherapy dose fractionation that they would recommend. Results: Among the 1013 board-certified radiation oncologists in Japan, 373 (36.8%) responded to the questionnaire. Most of the respondents (85.0%) believed that radiotherapy may be applicable as a primary treatment for hormone-naïve prostate cancer with bone metastases in some circumstances. For Case 1 (single bone metastasis), 55.0% of the respondents recommended radiotherapy for the prostate and bone metastasis. For Case 2 (three bone metastases), only 24.4% recommended radiotherapy for all lesions, and 31.4% recommended radiotherapy for the prostate only. For Case 3 (multiple bone metastases), 49.1% of the respondents stated that there was no indication for radiotherapy. However, 34% of the respondents still preferred to administer radiotherapy for the prostate. The radiotherapy techniques and dose fractionations varied widely among the respondents.

Objective To explore radiation oncologists’ attitudes and practice patterns of radiotherapy for hormone-naïve prostate cancer with bone metastases in Japan. Methods An internet-based survey was distributed to board-certified radiation oncologists of the Japanese Society of Radiation Oncology. Three hypothetical cases were assumed: hormone-naïve prostate cancer with single, three or multiple non-symptomatic bone metastases. The respondents described their attitude regarding such cases, treatment methods and the radiotherapy dose fractionation that they would recommend. Results Among the 1013 board-certified radiation oncologists in Japan, 373 (36.8%) responded to the questionnaire. Most of the respondents (85.0%) believed that radiotherapy may be applicable as a primary treatment for hormone-naïve prostate cancer with bone metastases in some circumstances. For Case 1 (single bone metastasis), 55.0% of the respondents recommended radiotherapy for the prostate and bone metastasis. For Case 2 (three bone metastases), only 24.4% recommended radiotherapy for all lesions, and 31.4% recommended radiotherapy for the prostate only. For Case 3 (multiple bone metastases), 49.1% of the respondents stated that there was no indication for radiotherapy. However, 34% of the respondents still preferred to administer radiotherapy for the prostate. The radiotherapy techniques and dose fractionations varied widely among the respondents. Conclusion Most of the respondent radiation oncologists believed that radiotherapy may be beneficial for hormone-naïve prostate cancer with bone metastases.

BACKGROUND Pharmacobiological behavior differs between gonadotropin-releasing hormone (GnRH) antagonists and GnRH agonists. However, reliable evidence clarifying the difference between them is limited. OBJECTIVES We aimed to elucidate the difference in recovery profile between GnRH antagonist (degarelix) and GnRH agonist (leuprorelin acetate or goserelin acetate) as short-term (12 weeks) neoadjuvant androgen deprivation therapy (ADT) prior to 125I-transperineal prostate brachytherapy (TPPB) for localized prostate cancer. MATERIALS AND METHODS This study was initially designed as a single-center, prospective, open-label, randomized controlled trial. The primary endpoint was a serum testosterone level above the castration range (>50 ng/dl) after the cessation of 12-week neoadjuvant ADT (GnRH antagonist or GnRH agonists). All patients underwent 12 weeks of neoadjuvant ADT. The recovery profiles of hormones, prostate-specific antigen, total prostate volume (TPV), bone mineral density, and quality of life scores were investigated. RESULTS Testosterone recovery duration after the last injection was significantly longer in the GnRH antagonist arm than in the GnRH agonist arm (median, 27.3 vs. 4.8 weeks, p < 0.001). The serum levels of luteinizing hormone and follicle-stimulating hormone in the GnRH antagonist arm also remained significantly lower than those in the GnRH agonist arm between 16 and 24 weeks (p < 0.01). Meanwhile, reduction in TPV at the time of TPPB was comparable between both arms (p = 0.128). There were also no significant between-arm differences in the International Prostate Symptom Score and the International Index of Erectile Function scores. DISCUSSION AND CONCLUSION The recovery patterns of hormonal profiles after short-term (12 weeks) neoadjuvant ADT differ between GnRH antagonists and GnRH agonists. The choice between these drugs matters and may have a clinical impact depending on the primary objective of ADT.

Previous studies have demonstrated excellent overall outcomes in patients who underwent low-dose-rate brachytherapy (LDR-BT) in intermediate-risk, localized prostate cancer (PCa). We thus investigated the appropriate length of time before completing prostate-specific antigen (PSA) monitoring after treatment. Between 2003 and 2014, 710 localized, intermediate-risk PCa patients underwent LDR-BT with or without supplemental external beam radiotherapy (EBRT). Data from 567 of those patients was analyzed in this study. Neoadjuvant hormonal therapy (NHT) was administered to 315 patients (55.6 %) and NHT with adjuvant hormonal therapy (AHT) to 59 patients (10.4 %), as per the protocol of a prospective randomized controlled trial (SHIP0804). We stratified patients by posttreatment PSA levels at specific times and assessed the factors for association with biochemical recurrence (BCR) and for clinical progression (CP). The median follow-up was 109 months (range, 60-205 months). Of 529 patients who were BCR-free at 3 years after treatment, 56 subsequently developed BCR, and 47 developed CP. PSA at 3 and 5 years after treatment were significantly correlated with long-term oncological outcomes. No patients with 5-year PSA levels ≤0.1 ng/mL subsequently developed BCR or CP. Discontinuation of PSA monitoring could be discussed with patients with intermediate-risk PCa as a reasonable option if PSA levels remain ≤0.1 ng/mL at 5 years after LDR-BT, either alone or with other combined modalities, as subsequent recurrences are quite rare.

Prostate-specific antigen (PSA) bounce after definitive radiotherapy has been reported as a predictor of improved biochemical recurrence-free survival (BCRFS). We revisited this phenomenon to confirm its clinical impact on oncological outcomes in patients with long-term follow-up who were free of biochemical recurrence (BCR) at least 3 years after treatment. A total of 541 patients with localized, intermediate-risk prostate cancer underwent low-dose rate brachytherapy with iodine-125 seeds with or without supplemental external beam radiotherapy in combination. Neoadjuvant hormonal therapy was administered to 273 patients (50.5%) with a median duration of 3 months (range 1–108 months). PSA bounce was defined as ≥ 0.2 ng/ml increase above the interval PSA nadir, followed by a decrease below that value. The median age was 69 years (range 49–90 years). The median follow-up duration was 102 months (range 36–205 months). One-hundred and fifty patients (27.7%) had PSA bounce with a median magnitude of 0.47 ng/ml (range 0.2–3.19 ng/ml). Age was significantly associated with the occurrence of PSA bounce [age: hazard ratio (HR) 0.95, 95% confidence interval (CI) 0.93–0.98]. It was found to be independently associated with a decreased risk for BCR (HR 0.29; 95% CI 0.12–0.69) and clinical progression (HR 0.44; 95% CI 0.95–0.98). PSA bounce indicated a favorable BCRFS and clinical progression-free survival in patients who had been free of BCR for at least 3 years after definitive radiotherapy.

Purpose To assess the outcomes of high-dose-rate (HDR) brachytherapy and hypofractionated external beam radiation therapy (EBRT) combined with long-term androgen deprivation therapy (ADT) in very-high-risk (VHR) versus high-risk (HR) prostate cancer (PCa), as defined in the National Comprehensive Cancer Network (NCCN) criteria. Methods Data from 338 consecutive HR or VHR PCa patients who had undergone this tri-modal therapy between 2005 and 2018 were retrospectively analyzed. Biochemical recurrence (BCR)-free, progression-free, overall, and cancer-specific survival (BCRFS/PFS/OS/CSS) rates were analyzed using the Kaplan–Meier method and Wilcoxon test. Cox regression models were used to evaluate candidate prognostic factors for survival. C‑indexes were used to assess model discrimination. Results Within a median follow-up of 84 months, 68 patients experienced BCR, 58 had disease progression including only 3 with local progression, 27 died of any cause, and 2 died from PCa. The 5‑year BCRFS, PFS, OS, and CSS rates were 82.2% (HR 86.5%; VHR 70.0%), 90.0% (HR 94.3%; VHR 77.6%), 95.7% (HR, 97.1%; VHR, 91.8%), and 99.6% (HR, 100%; VHR, 98.0%), respectively. In multivariable analyses that adjusted for standard clinicopathologic features, the risk subclassification was associated both PFS and OS (p = 0.0003 and 0.001, respectively). Adding the risk subclassification improved the accuracy of models in predicting BCRFS, PFS, and OS. Conclusion While the outcome of this trimodal approach appears favorable, VHR PCa patients had significantly worse oncological outcomes than those with HR PCa. The NCCN risk subclassification should be integrated into prognostic tools to guide risk stratification, treatment, and follow-up for unfavorable PCa patients receiving this trimodal therapy.

HIV-1 protease inhibitors (PIs), such as darunavir (DRV), are the key component of antiretroviral therapy. However, HIV-1 often acquires resistance to PIs. Here, seven novel PIs were synthesized, by introducing single atom changes such as an exchange of a sulfur to an oxygen, scission of a single bond in P2′-cyclopropylaminobenzothiazole (or -oxazole), and/or P1-benzene ring with fluorine scan of mono- or bis-fluorine atoms around DRV’s scaffold. X-ray structural analyses of the PIs complexed with wild-type Protease (PRWT) and highly-multi-PI-resistance-associated PRDRVRP51 revealed that the PIs better adapt to structural plasticity in PR with resistance-associated amino acid substitutions by formation of optimal sulfur bond and adaptation of cyclopropyl ring in the S2′-subsite. Furthermore, these PIs displayed increased cell permeability and extreme anti-HIV-1 potency compared to DRV. Our work provides the basis for developing novel PIs with high potency against PI-resistant HIV-1 variants with a high genetic barrier.

We describe here design, synthesis, and biological evaluation of a series of highly potent HIV-1 protease inhibitors containing stereochemically defined and unprecedented tricyclic furanofuran derivatives as P2 ligands in combination with a variety of sulfonamide derivatives as P2’ ligands. These inhibitors were designed to enhance the ligand-backbone binding and van der Waals interactions in the protease active site. A number of inhibitors containing the new P2 ligand, an aminobenzothiazole as the P2’ ligand and a difluorophenylmethyl as the P1 ligand, displayed very potent enzyme inhibitory potency and also showed excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The tricyclic P2 ligand has been synthesized efficiently in an optically active form using enzymatic desymmetrization of meso-1,2-(dihydroxymethyl)cyclohex-4-ene as the key step. We determined high-resolution X-ray structures of inhibitor-bound HIV-1 protease. These structures revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insights into the binding properties of these new inhibitors.

Investigating oncological outcomes in patients registered in the Japanese Prostate Cancer Outcome Study of Permanent Iodine-125 Seed Implantation (J-POPS) in terms of biochemical relapse-free survival (bRFS) by the Phoenix and the newly developed J-POPS definitions, exploration of predictive factors for bRFS, and preliminary verification of pitfalls of prostate-specific antigen (PSA) failure definitions. Between July 2005 and June 2007, 2316 clinically localized patients underwent permanent seed implantation. The primary endpoint was bRFS. One of the secondary endpoints was overall survival (OS). The median age was 69 and performance status was 0 in 99.1% of participants. The median biologically effective dose (BED) was about 180 Gy2. During a median follow-up of 60.0 months, 8.4 and 5.9% had PSA failure by the Phoenix and the J-POPS definitions, respectively. The 5-year bRFSs based on the Phoenix and the J-POPS definitions were 89.1 and 91.6%, respectively. The 5-year OS was 97.3%. According to multivariate analyses, only age affected bRFS based on the Phoenix definition, whereas the risk group and BED independently affected bRFS based on the J-POPS definition. A spontaneous PSA decrease was seen in 91.1% of participants after PSA failure based on the Phoenix definition alone, but in only 22.2% after PSA failure based on the J-POPS definition alone. The world’s largest registration study, J-POPS, consisted of patients with longevity, and a highly quality-controlled BED resulted in excellent bRFS and OS. The high likelihood of PSA bounce by the Phoenix definition should be taken into account, especially in younger patients. NCT00534196.

The design, synthesis, and biological evaluation of a new class of HIV-1 protease inhibitors containing stereochemically defined fused tricyclic polyethers as the P2 ligands and a variety of sulfonamide derivatives as the P2′ ligands, are described. A number of ring sizes and various substituent effects were investigated to enhance the ligand-backbone interactions in the protease active site. Inhibitors 5c and 5d containing this unprecedented fused 6-5-5 ring system as the P2 ligand, an aminobenzothiazole as the P2′ ligand and a difluorophenylmethyl as the P1 ligand exhibited exceptional enzyme inhibitory potency and maintained excellent antiviral activity against a panel of highly multidrug-resistant HIV-1 variants. The umbrella-like P2 ligand for these inhibitors has been synthesized efficiently in an optically active form using a Pauson-Khand cyclization reaction as the key step. The racemic alcohols were resolved efficiently using a lipase catalyzed enzymatic resolution. Two high resolution X-ray structures of inhibitor-bound HIV-1 protease revealed extensive interactions with the backbone atoms of HIV-1 protease and provided molecular insight into the binding properties of these new inhibitors.

In this paper, we report a new method using pickup coils on a diaphragm to locate a mechanical disturbance source in a superconducting coil. Pickup coils with a twisted pair cable have a lower heat penetration compared to acoustic emission (AE) sensors with a coaxial cable. Vibrations of the diaphragm, which are caused by an acoustic pressure wave from a mechanical disturbance source, vibrate the pickup coil in an inhomogeneous magnetic field and generate signals in the pickup coils as inductive voltages. We have applied pickup coils to locate the azimuthal position of mechanical disturbance sources, which induce superconducting magnet quenching. The azimuth position of the mechanical disturbance sources have been located by measuring the time differences of the acoustic wave arrival at each pickup coil. The results using the pickup coils and AE sensors agreed in the angular range below 38°. The measurement error of this method was caused mainly by the detection time lag due to the acoustic wave damping in the coil windings.

Employing NOD/SCID/Jak3-/- mice transplanted with human PBMCs (hNOJ mice) and replication-competent, red-fluorescent-protein (mCherry; mC)-labeled HIV-1JR-FL (HIVmC), we examined whether early antiretroviral treatment blocked the establishment of HIV-1 infection. The use of hNOJ mice and HIVmC enabled us to visually locate infection foci and to examine the early dynamics of HIVmC infection without using a large amount of antiretroviral unlike in non-human primate models. Although when raltegravir (RAL) administration was begun 1 day after intraperitoneal (ip) inoculation of HIVmC, no plasma p24 or plasma HIV-1-RNA (pRNA) were detected in 10 of 12 hNOJ (hNOJmCRAL+) mice as assessed on the last day of the 14-day continuous twice-daily RAL administration, all 10 untreated hNOJmC (hNOJmCRAL-) mice became positive for p24 and pRNA and had significantly swollen lymph nodes in peritoneal cavity and abundant p24+/mC+/CD3+/CD4+ T cells and p24+/mC+/CD68+ monocytes/macrophages were identified in their omenta and mesenteric lymphoid tissues/lymph nodes upon necropsy of the mice on day 14. In 12 hNOJmCRAL+ mice, no significantly swollen lymph nodes were seen compared to hNOJmCRAL- mice; however, in the omentum of the 2 hNOJmCRAL+ mice that were positive for pRNA and in site RNA, mC+/p24+/CD3+/CD83+ cells were identified, suggesting that viral breakthrough occurred later in the observation period. The present data suggest that the use of hNOJ mouse model and HIVmC may shed light on the study of early-phase dynamics of HIV-1 infection and cellular events in post-exposure/pre-exposure prophylaxis.

We designed, synthesized, and identified two novel nonpeptidic HIV-1 protease inhibitors (PIs), GRL- 037 and GRL-044, containing P2-tetrahydropyrano-tetrahydrofuran (Tp-THF), P1-benzene and P1-methoxybenzene, respectively, and P2'-isopropyl-aminobenzothiazole (Ip-Abt), based on the structure of the prototypic PI, darunavir (DRV). The 50% inhibitory concentrations (IC(50)s) of GRL-037 and GRL-044 against wild-type HIV-1(NL4-3) were 0.042 and 0.0028-0.0033 nM with minimal cytotoxicity profiles compared to the IC(50) values of four most potent FDA-approved PIs, ranging from 2.6 to 70 nM. GRL-044 was also potent against HIV-2EHO (IC(50)=0.0004 nM) and various PI-resistant HIV-1 variants (IC(50) ranging from 0.065 to 19 nM). In the selection assays we conducted, the emergence of HIV-1 variants resistant to GRL-044 was significantly delayed compared to that against DRV. Thermal stability test using differential scanning fluorimetry employing purified HIV-1 protease (PR) and SYPRO(®) Orange showed that both GRL-037 and GRL-044 tightly bound to PR. A28S substitution emerged in the homologous recombination-based selection assays with GRL-044. Structural analyses showed that the larger size of GRL-044 over DRV, enabling GRL-044 to fit better to the hydrophobic cavity of protease, contributed to the greater potency of GRL- 044 against HIV-1. Structural analyses also suggested that the van der Waals surface contact of GRL-044 with A28' appears to be better compared to that of DRV because of the larger surface of Ip-Abt of GRL-044, which may be partially responsible for the emergence of A28S. The present antiviral data and structural features of GRL-044 should provide molecular insights for further design and development of potent and "resistance-repellant" novel PIs.

Hepatitis B virus (HBV) infection is a major worldwide health problem that requires the development of improved antiviral therapies. Here, a series of 4′-Azido-thymidine/4′-Azido-2′-deoxy-5-methylcytidine derivatives (6, 10-15) were synthesized, and their anti-HBV activities evaluated. Compounds 10–15 were synthesized via an S(N)Ar reaction of 18, in which the 4-position of the thymine moiety was activated as the 2,4,6-triisopropylbenzenesulfonate. Compounds 11–15 showed no antiviral activity. However, 4′-Azido thymidine (6) and 4′-Azido-2′-deoxy-5-methylcytidine (10) displayed significant anti-HBV activity (EC(50) = 0.63 and 5.99 μM, respectively) with no detectable cytotoxicity against MT-2 cells up to 100 μM.

We report here the synthesis and biological evaluation of phenylcarboxylic acid and phenylboronic acid containing HIV-1 protease inhibitors and their functional effect on enzyme inhibition and antiviral activity in MT-2 cell lines. Inhibitors bearing bis-THF ligand as P2 ligand and phenylcarboxylic acids and carboxamide as the P2’ ligands, showed very potent HIV-1 protease inhibitory activity. However, carboxylic acid containing inhibitors showed very poor antiviral activity compared to carboxamide-derived inhibitors which showed good antiviral IC(50) value. Boronic acid-derived inhibitor with bis-THF as the P2 ligand showed very potent enzyme inhibitory activity, but it showed relatively reduced antiviral activity compared to darunavir in the same assay. Boronic acid-containing inhibitor with a P2-Crn-THF ligand also showed potent enzyme K(i) but significantly reduced antiviral activity. We have evaluated antiviral activity against a panel of highly drug-resistant HIV-1 variants. One of the inhibitors maintained good antiviral activity against HIV(DRV)(R)(P20) and HIV(DRV)(R)(P30) viruses. We have determined high resolution X-ray structures of two synthetic inhibitors bound to HIV-1 protease and obtained molecular insight into the ligand-binding site interactions.

Combination antiretroviral therapy has achieved dramatic reductions in the mortality and morbidity in people with HIV-1 infection. Darunavir (DRV) represents a most efficacious and well-tolerated protease inhibitor (PI) with a high genetic barrier to the emergence of drug-resistant HIV-1. However, highly DRV-resistant variants have been reported in patients receiving long-term DRV-containing regimens. Here, we report three novel HIV-1 PIs (GRL-057-14, GRL-058-14, and GRL-059-14), all of which contain a P2-amino-substituted-bis-tetrahydrofuranylurethane (bis-THF) and a P2'-cyclopropyl-amino-benzothiazole (Cp-Abt). These PIs not only potently inhibit the replication of wild-type HIV-1 (50% effective concentration [EC50], 0.22 nM to 10.4 nM) but also inhibit multi-PI-resistant HIV-1 variants, including highly DRV-resistant HIVDRV R P51 (EC50, 1.6 nM to 30.7 nM). The emergence of HIV-1 variants resistant to the three compounds was much delayed in selection experiments compared to resistance to DRV, using a mixture of 11 highly multi-PI-resistant HIV-1 isolates as a starting HIV-1 population. GRL-057-14 showed the most potent anti-HIV-1 activity and greatest thermal stability with wild-type protease, and potently inhibited HIV-1 protease's proteolytic activity (Ki value, 0.10 nM) among the three PIs. Structural models indicate that the C-5-isopropylamino-bis-THF moiety of GRL-057-14 forms additional polar interactions with the active site of HIV-1 protease. Moreover, GRL-057-14's P1-bis-fluoro-methylbenzene forms strong hydrogen bonding and effective van der Waals interactions. The present data suggest that the combination of C-5-aminoalkyl-bis-THF, P1-bis-fluoro-methylbenzene, and P2'-Cp-Abt confers highly potent activity against wild-type and multi-PI-resistant HIV strains and warrant further development of the three PIs, in particular, that of GRL-057-14, as potential therapeutic for HIV-1 infection and AIDS.

We describe the design, synthesis, and biological evaluation of novel HIV-1 protease inhibitors containing a squaramide-derived scaffold as the P2 ligand in combination with a (R)-hydroxyethylamine sulfonamide isostere. Inhibitor 3h with an N-methyl-3-(R)-aminotetrahydrofuranyl squaramide P2-ligand displayed an HIV-1 protease inhibitory Ki value of 0.51 nM. An energy minimized model of 3h revealed the major molecular interactions between HIV-1 protease active site and the tetrahydrofuranyl squaramide scaffold that may be responsible for its potent activity.

The present study examined the efficacy and complications associated with intensity-modulated radiation therapy (IMRT) for optic nerve sheath meningioma (ONSM) in 15 cases and compared visual function before and after treatment. Consecutively diagnosed patients with ONSM treated with IMRT were evaluated from 2012 to 2017. We categorized ONSM with three growth patterns (diffuse, fusiform, or globular). Visual acuity, visual fields, and optic disc findings were assessed before and after IMRT. Ocular and systemic complications were evaluated during and after treatment. The 15 patients selected for analysis ranged in age from 33 to 77 years. Post-treatment observation periods were 8 to 57 months. After IMRT, tumor enlargement was not detected in any eyes, and tumor reduction was seen in 2 eyes. At final post-treatment follow-up, eyes with fusiform and globular growth maintained better visual acuity compared with pre-treatment, whereas 2 of 5 eyes with diffuse growth showed reduced vision. Five eyes with no apparent optic disc abnormality maintained better visual acuity compared with pre-treatment, whereas 8 of 10 eyes with disc edema and atrophy remained stable or showed reduced vision. Improvements were seen in all 5 eyes with optic discs negative for pre-treatment abnormalities. Final post-treatment visual field abnormalities improved in 11 eyes. All adverse events identified during IMRT improved rapidly during the treatment period. IMRT for the treatment of ONSM achieved improvement and preserved visual function. In particular, early treatment with IMRT before the appearance of optic disc abnormalities can be more effective for improving visual function.

Combination antiretroviral therapy has achieved dramatic reductions in the mortality and morbidity in people with HIV-1 infection. Darunavir (DRV) represents a most efficacious and well-tolerated protease inhibitor (PI) with a high genetic barrier to the emergence of drug-resistant HIV-1. However, highly DRV-resistant variants have been reported in patients receiving long-term DRV-containing regimens. Here, we report three novel HIV-1 PIs (GRL-057-14, GRL-058-14, and GRL-059-14), all of which contain a P2-amino-substituted-bis-tetrahydrofuranylurethane (bis-THF) and a P2′-cyclopropyl-amino-benzothiazole (Cp-Abt). These PIs not only potently inhibit the replication of wild-type HIV-1 (50% effective concentration [EC(50)], 0.22 nM to 10.4 nM) but also inhibit multi-PI-resistant HIV-1 variants, including highly DRV-resistant HIV(DRV)(R)(P51) (EC(50), 1.6 nM to 30.7 nM). The emergence of HIV-1 variants resistant to the three compounds was much delayed in selection experiments compared to resistance to DRV, using a mixture of 11 highly multi-PI-resistant HIV-1 isolates as a starting HIV-1 population. GRL-057-14 showed the most potent anti-HIV-1 activity and greatest thermal stability with wild-type protease, and potently inhibited HIV-1 protease’s proteolytic activity (K(i) value, 0.10 nM) among the three PIs. Structural models indicate that the C-5-isopropylamino-bis-THF moiety of GRL-057-14 forms additional polar interactions with the active site of HIV-1 protease. Moreover, GRL-057-14’s P1-bis-fluoro-methylbenzene forms strong hydrogen bonding and effective van der Waals interactions. The present data suggest that the combination of C-5-aminoalkyl-bis-THF, P1-bis-fluoro-methylbenzene, and P2ʹ-Cp-Abt confers highly potent activity against wild-type and multi-PI-resistant HIV strains and warrant further development of the three PIs, in particular, that of GRL-057-14, as potential therapeutic for HIV-1 infection and AIDS.

We generated two novel nonpeptidic HIV-1 protease inhibitors (PIs), GRL-001-15 and GRL-003-15, which contain unique crown-like tetrahydropyranofuran (Crn-THF) and P2′-cyclopropyl-aminobenzothiazole (Cp-Abt) moieties as P2 and P2′ ligands, respectively. GRL-001-15 and GRL-003-15 have meta-monofluorophenyl and para-monofluorophenyl at the P1 site, respectively, exert highly potent activity against wild-type HIV-1 with 50% effective concentrations (EC(50)s) of 57 and 50 pM, respectively, and have favorable cytotoxicity profiles with 50% cytotoxic concentrations (CC(50)s) of 38 and 11 μM, respectively. The activity of GRL-001-15 against multi-PI-resistant HIV-1 variants was generally greater than that of GRL-003-15. The EC(50) of GRL-001-15 against an HIV-1 variant that was highly resistant to multiple PIs, including darunavir (DRV) (HIV-1(DRV)(R)(P30)), was 0.17 nM, and that of GRL-003-15 was 3.3 nM, while DRV was much less active, with an EC(50) of 216 nM. The emergence of HIV-1 variants resistant to GRL-001-15 and GRL-003-15 was significantly delayed compared to that of variants resistant to selected PIs, including DRV. Structural analyses of wild-type protease (PR(WT)) complexed with the novel PIs revealed that GRL-001-15’s meta-fluorine atom forms halogen bond interactions (2.9 and 3.0 Å) with Gly49 and Ile50, respectively, of the protease flap region and with Pro81′ (2.7 and 3.2 Å), which is located close to the protease active site, and that two fluorine atoms of GRL-142-13 form multiple halogen bond interactions with Gly49, Ile50, Pro81′, Ile82′, and Arg8′. In contrast, GRL-003-15 forms halogen bond interactions with Pro81′ alone, suggesting that the reduced antiviral activity of GRL-003-15 is due to the loss of the interactions with the flap region.

A method for the diastereoselective synthesis of 6″-(Z)- and 6″-(E)-fluorinated analogues of the anti-HBV agent entecavir has been developed. Construction of the methylenecyclopentane skeleton of the target molecules has been accomplished by radical-mediated 5-exo-dig cyclization of the selenides 6 and 15 having the phenylsulfanylethynyl structure as a radical accepting moiety. In the radical reaction of the TBS-protected precursor 6, (Z)-anti-12 was formed as a major product. On the other hand, TIPS-protected 15 gave (E)-anti-12. The sulfur-extrusive stannylation of anti-12 furnished a mixture of geometric isomers of the respective vinylstannane, whereas benzoyl-protected 17 underwent the stannylation in the manner of retention of configuration. Following XeF(2)-mediated fluorination, introduction of the purine base and deoxygenation of the resulting carbocyclic guanosine gave the target (E)- and (Z)-3 after deprotection. Evaluation of the anti-HBV activity of 3 revealed that fluorine-substitution at the 6″-position of entecavir gave rise to a reduction in the cytotoxicity in HepG2 cells with retention of the antiviral activity.

This study investigates the heat exchanger structure for the solid nitrogen heat capacitor, which slows the warming rate of the superconducting magnet during a power failure. To improve transient heat transfer of the solid nitrogen, the heat exchanger has a vertically layered structure to limit the thickness of the solid nitrogen. Horizontally wide heat transfer fins maintain thermal contact using the weight of the solid nitrogen. The heat exchanger solidified 2000 cm 3 of liquid nitrogen in one hour and cooled the HTS coil to the operating temperature using just the cryocooler. In the temperature rise test, which stopped the cryocooler for one hour, it was estimated that the heat exchanger utilizes 28.3%-35.1% of the heat capacity of the solid nitrogen.

We identified three nonpeptidic HIV-1 protease inhibitors (PIs), GRL-015, -085, and -097, containing tetrahydropyrano-tetrahydrofuran (Tp-THF) with a C-5 hydroxyl. The three compounds were potent against a wild-type laboratory HIV-1 strain (HIV-1 WT ), with 50% effective concentrations (EC 50 s) of 3.0 to 49 nM, and exhibited minimal cytotoxicity, with 50% cytotoxic concentrations (CC 50 ) for GRL-015, -085, and -097 of 80, >100, and >100 μM, respectively. All the three compounds potently inhibited the replication of highly PI-resistant HIV-1 variants selected with each of the currently available PIs and recombinant clinical HIV-1 isolates obtained from patients harboring multidrug-resistant HIV-1 variants (HIV MDR ). Importantly, darunavir (DRV) was >1,000 times less active against a highly DRV-resistant HIV-1 variant (HIV-1 DRV R P51 ); the three compounds remained active against HIV-1 DRV R P51 with only a 6.8- to 68-fold reduction. Moreover, the emergence of HIV-1 variants resistant to the three compounds was considerably delayed compared to the case of DRV. In particular, HIV-1 variants resistant to GRL-085 and -097 did not emerge even when two different highly DRV-resistant HIV-1 variants were used as a starting population. In the structural analyses, Tp-THF of GRL-015, -085, and -097 showed strong hydrogen bond interactions with the backbone atoms of active-site amino acid residues (Asp29 and Asp30) of HIV-1 protease. A strong hydrogen bonding formation between the hydroxyl moiety of Tp-THF and a carbonyl oxygen atom of Gly48 was newly identified. The present findings indicate that the three compounds warrant further study as possible therapeutic agents for treating individuals harboring wild-type HIV and/or HIV MDR . IMPORTANCE Darunavir (DRV) inhibits the replication of most existing multidrug-resistant HIV-1 strains and has a high genetic barrier. However, the emergence of highly DRV-resistant HIV-1 strains (HIV DRV R ) has recently been observed in vivo and in vitro . Here, we identified three novel HIV-1 protease inhibitors (PIs) containing a tetrahydropyrano-tetrahydrofuran (Tp-THF) moiety with a C-5 hydroxyl (GRL-015, -085, and -097) which potently suppress the replication of HIV DRV R . Moreover, the emergence of HIV-1 strains resistant to the three compounds was considerably delayed compared to the case of DRV. The C-5 hydroxyl formed a strong hydrogen bonding interaction with the carbonyl oxygen atom of Gly48 of protease as examined in the structural analyses. Interestingly, a compound with Tp-THF lacking the hydroxyl moiety substantially decreased activity against HIV DRV R . The three novel compounds should be further developed as potential drugs for treating individuals harboring wild-type and multi-PI-resistant HIV variants as well as HIV DRV R .

Darunavir (DRV) has bimodal activity against HIV-1 protease, enzymatic inhibition and protease dimerization inhibition, and has an extremely high genetic barrier against development of drug resistance. We previously generated a highly DRV-resistant HIV-1 variant (HIVDRVRP51). We also reported that four amino acid substitutions (V32I, L33F, I54M, and I84V) identified in the protease of HIVDRVRP51 are largely responsible for its high-level resistance to DRV. Here, we attempted to elucidate the role of each of the four amino acid substitutions in the development of DRV resistance. We found that V32I is a key substitution, which rarely occurs, but once it occurs, it predisposes HIV-1 to develop high-level DRV resistance. When two infectious recombinant HIV-1 clones carrying I54M and I84V (rHIVI54M and rHIVI84V, respectively) were selected in the presence of DRV, V32I emerged, and the virus rapidly developed high-level DRV resistance. rHIVV32I also developed high-level DRV resistance. However, wild-type HIVNL4-3 (rHIVWT) failed to acquire V32I and did not develop DRV resistance. Compared to rHIVWT, rHIVV32I was highly susceptible to DRV and had significantly reduced fitness, explaining why V32I did not emerge upon selection of rHIVWT with DRV. When the only substitution is at residue 32, structural analysis revealed much stronger van der Waals interactions between DRV and I-32 than between DRV and V-32. These results suggest that V32I is a critical amino acid substitution in multiple pathways toward HIV-1’s DRV resistance development and elucidate, at least in part, a mechanism of DRV’s high genetic barrier to development of drug resistance. The results also show that attention should be paid to the initiation or continuation of DRV-containing regimens in people with HIV-1 containing the V32I substitution., IMPORTANCE Darunavir (DRV) is the only protease inhibitor (PI) recommended as a first-line therapeutic and represents the most widely used PI for treating HIV-1-infected individuals. DRV possesses a high genetic barrier to development of HIV-1’s drug resistance. However, the mechanism(s) of the DRV’s high genetic barrier remains unclear. Here, we show that the preexistence of certain single amino acid substitutions such as V32I, I54M, A71V, and I84V in HIV-1 protease facilitates the development of high-level DRV resistance. Interestingly, all in vitro-selected highly DRV-resistant HIV-1 variants acquired V32I but never emerged in wild-type HIV (HIVWT), and V32I itself rendered HIV-1 more sensitive to DRV and reduced viral fitness compared to HIVWT, strongly suggesting that the emergence of V32I plays a critical role in the development of HIV-1’s resistance to DRV. Our results would be of benefit in the treatment of HIV-1-infected patients receiving DRV-containing regimens.

We identified four novel nonpeptidic human immunodeficiency virus type 1 (HIV-1) protease inhibitors (PIs), GRL-078, -079, -077, and -058, containing an alkylamine at the C-5 position of P2 tetrahydropyrano-tetrahydrofuran (Tp-THF) and a P2′ cyclopropyl (Cp) (or isopropyl)-aminobenzothiazole (Abt) moiety. Their 50% effective concentrations (EC 50 s) were 2.5 to 30 nM against wild-type HIV-1 NL4-3 , 0.3 to 6.7 nM against HIV-2 EHO , and 0.9 to 90 nM against laboratory-selected PI-resistant HIV-1 and clinical HIV-1 variants resistant to multiple FDA-approved PIs (HIV MDR ). GRL-078, -079, -077, and -058 also effectively blocked the replication of HIV-1 variants highly resistant to darunavir (DRV) (HIV DRV r p51 ), with EC 50 s of 38, 62, 61, and 90 nM, respectively, while four FDA-approved PIs examined (amprenavir, atazanavir, lopinavir [LPV], and DRV) had virtually no activity (EC 50 s of >1,000 nM) against HIV DRV r p51 . Structurally, GRL-078, -079, and -058 form strong hydrogen bond interactions between Tp-THF modified at C-5 and Asp29/Asp30/Gly48 of wild-type protease, while the P2′ Cp-Abt group forms strong hydrogen bonds with Asp30′. The Tp-THF and Cp-Abt moieties also have good nonpolar interactions with protease residues located in the flap region. For selection with LPV and DRV by use of a mixture of 11 HIV MDR strains (HIV 11MIX ), HIV 11MIX became highly resistant to LPV and DRV over 13 to 32 and 32 to 41 weeks, respectively. However, for selection with GRL-079 and GRL-058, HIV 11MIX failed to replicate at >0.08 μM and >0.2 μM, respectively. Thermal stability results supported the highly favorable anti-HIV-1 potency of GRL-079 as well as other PIs. The present data strongly suggest that the P2 Tp-THF group modified at C-5 and the P2′ Abt group contribute to the potent anti-HIV-1 profiles of the four PIs against HIV-1 NL4-3 and a wide spectrum of HIV MDR strains.

Herein we report the design, synthesis, X-ray structural, and biological studies of an exceptionally potent HIV-1 protease inhibitor, compound 5 ((3S,7aS,8S)-hexahydro-4H-3,5-methanofuro[2,3-b]pyran-8-yl ((2S,3R)-4-((2-(cyclopropylamino)-N-isobutylbenzo[d]thiazole)-6-sulfonamido)-1-(3,5-difluorophenyl)-3-hydroxybutan-2-yl)carbamate). Using structure-based design, we incorporated an unprecedented 6-5-5-ring-fused crown-like tetrahydropyranofuran as the P2-ligand, a cyclopropylaminobenzothiazole as the P2'-ligand, and a 3,5-difluorophenylmethyl group as the P1-ligand. The resulting inhibitor 5 exhibited exceptional HIV-1 protease inhibitory and antiviral potency at the picomolar level. Furthermore, it displayed antiviral IC50 values in the picomolar range against a wide panel of highly multidrug-resistant HIV-1 variants. The inhibitor shows an extremely high genetic barrier against the emergence of drug-resistant variants. It also showed extremely potent inhibitory activity toward dimerization as well as favorable central nervous system penetration. We determined a high-resolution X-ray crystal structure of the complex between inhibitor 5 and HIV-1 protease, which provides molecular insight into the unprecedented activity profiles observed.

We describe the design, synthesis and biological evaluation of a series of novel HIV-1 protease inhibitors bearing isophthalamide derivatives as the P2–P3 ligands. We have investigated a range of acyclic and heterocyclic amides as the extended P2–P3 ligands. These inhibitors displayed good to excellent HIV-1 protease inhibitory activity. Also, a number of inhibitors showed very good antiviral activity in MT cells. Compound 5n has shown an enzyme Ki of 0.17 nM and antiviral IC50 of 14 nM. An X-ray crystal structure of inhibitor 5o-bound to HIV-1 protease was determined at 1.11 A resolution. This structure revealed important molecular insight into the inhibitor–HIV-1 protease interactions in the active site.

Certain nucleoside/nucleotide reverse transcriptase (RT) inhibitors (NRTIs) are effective against human immunodeficiency virus type 1 (HIV-1) and hepatitis B virus (HBV). However, both viruses often acquire NRTI resistance, making it crucial to develop more-potent agents that offer profound viral suppression. Here, we report that 4′-C-cyano-2-amino-2′-deoxyadenosine (CAdA) is a novel, highly potent inhibitor of both HBV (half maximal inhibitory concentration [IC50] = 0.4 nM) and HIV-1 (IC50 = 0.4 nM). In contrast, the approved anti-HBV NRTI, entecavir (ETV), potently inhibits HBV (IC50 = 0.7 nM), but is much less active against HIV-1 (IC50 = 1,000 nM). Similarly, the highly potent HIV-1 inhibitor, 4′-ethynyl-2-fluoro-2′-deoxyadenosine (EFdA; IC50 = 0.3 nM) is less active against HBV (IC50 = 160 nM). Southern analysis using Huh-7 cells transfected with HBV-containing plasmids demonstrated that CAdA was potent against both wild-type (IC50 = 7.2 nM) and ETV-resistant HBV (IC50 = 69.6 nM for HBVETV‐RL180M/S202G/M204V), whereas ETV failed to reduce HBVETV‐RL180M/S202G/M204V DNA even at 1 μM. Once-daily peroral administration of CAdA reduced HBVETV‐RL180M/S202G/M204V viremia (P = 0.0005) in human-liver-chimeric/ HBVETV‐RL180M/S202G/M204V–infected mice, whereas ETV completely failed to reduce HBVETV‐RL180M/S202G/M204V viremia. None of the mice had significant drug-related body-weight or serum human-albumin concentration changes. Molecular modeling suggests that a shallower HBV-RT hydrophobic pocket at the polymerase active site can better accommodate the slightly shorter 4′-cyano of CAdA-triphosphate (TP), but not the longer 4′-ethynyl of EFdA-TP. In contrast, the deeper HIV-1-RT pocket can efficiently accommodate the 4′-substitutions of both NRTIs. The ETV-TP's cyclopentyl ring can bind more efficiently at the shallow HBV-RT binding pocket. Conclusion: These data provide insights on the structural and functional associations of HBV- and HIV-1-RTs and show that CAdA may offer new therapeutic options for HBV patients. (Hepatology 2015;62:1024-1036)

The conditions and outcomes of Japanese patients with prostate cancer who developed PSA failure after radical prostatectomy (RP), and who were treated via salvage radiotherapy (S-RT), were surveyed. Clinical data on S-RT were gathered in questionnaires completed by facilities participating in the Japanese Radiation Oncology Study Group. S-RT was defined as external-beam radiotherapy delivered to the prostate beds of patients with prostate cancer who had eventually developed PSA failure, although their PSA values had at one stage attained levels 0.3 ng/ml (57.5% vs 40.5%, P = 0.027). In Japan, hormonal therapy is combined with S-RT in ∼40% of cases. The 5-year PRFS and CFFS rates of cases treated via S-RT alone were 50.1% and 90.1%, respectively. A PSA value of 0.3 ng/ml served as a significant cut-off for prediction of PRFS.

To investigate contemporary rates of variation in the biopsy Gleason grading in prostate cancer, between local and central pathologists, based on central review of the pathological slides from Seed and Hormone for Intermediate-risk Prostate Cancer (SHIP) 0804, a phase III, multicenter, randomized, controlled study. From April 2008 to May 2011, 18 Japanese institutions participated. All HE with the under-grading and over-grading of grades to be 14.6% and 20.1%, respectively. The central review resulted in numbers of tumor-bearing cores reassigned in 99 of 616 cases in which such information by the local pathologists was available (16.1%). Discordance in biopsy Gleason grading was still found in one third of the cases in the SHIP0804 study. This information is valuable in extrapolating the diagnostic error range in contemporary clinical studies conducted without central pathological review.

Background Monocytes and neutrophils are activated during disseminated intravascular coagulation. Tissue factor, the main initiator of coagulation, is expressed by monocytes, while elastase is released by neutrophils. Aims This study investigated tissue factor production by peripheral monocytes after stimulation with human neutrophil elastase. Methods Tissue factor mRNA levels were investigated by the reverse transcriptase-polymerase chain reaction and tissue factor protein production was assessed by western blotting when monocytes were exposed to neutrophil elastase with or without preincubation using various inhibitors. Results Neutrophil elastase upregulated tissue factor mRNA and protein levels in monocytes. Both U73122 (phospholipase C inhibitor) and TMB-8 (intracellular calcium antagonist) prevented the upregulation of tissue factor mRNA. SB203580 (p38 mitogen-activated protein kinase inhibitor) suppressed this response, but PD98059 (extracellular signal-regulated kinase inhibitor) did not. Ro-318425 (ATP-competitive and selective protein kinase C (PKC) inhibitor) and Go 6976 (inhibitor of conventional PKCs and PKCμ) blocked the upregulation of tissue factor mRNA expression. Go 6983 (broad-spectrum PKC inhibitor) and CGP 4125 (staurosporine analog) partially attenuated it, as did a PKC theta/delta inhibitor. Conclusions Neutrophil elastase mainly enhances tissue factor production by monocytes via the phospholipase C/conventional PKC/p38 MAPK pathway, although a novel PKC is also involved.

Antiretroviral therapy for HIV-1 infection/AIDS has significantly extended the life expectancy of HIV-1-infected individuals and reduced HIV-1 transmission at very high rates. However, certain individuals who initially achieve viral suppression to undetectable levels may eventually suffer treatment failure mainly due to adverse effects and the emergence of drug-resistant HIV-1 variants. Here, we report GRL-142, a novel HIV-1 protease inhibitor containing an unprecedented 6-5-5-ring-fused crown-like tetrahydropyranofuran, which has extremely potent activity against all HIV-1 strains examined with IC50 values of attomolar-to-picomolar concentrations, virtually no effects on cellular growth, extremely high genetic barrier against the emergence of drug-resistant variants, and favorable intracellular and central nervous system penetration. GRL-142 forms optimum polar, van der Waals, and halogen bond interactions with HIV-1 protease and strongly blocks protease dimerization, demonstrating that combined multiple optimizing elements significantly enhance molecular and atomic interactions with a target protein and generate unprecedentedly potent and practically favorable agents.

Design, synthesis, and evaluation of a new class of HIV-1 protease inhibitors containing diverse flexible macrocyclic P1′–P2′ tethers are reported. Inhibitor 5a with a pyrrolidinone-derived macrocycle exhibited favorable enzyme inhibitory and antiviral activity (Ki = 13.2 nM, IC50 = 22 nM). Further incorporation of heteroatoms in the macrocyclic skeleton provided macrocyclic inhibitors 5m and 5o. These compounds showed excellent HIV-1 protease inhibitory (Ki = 62 pM and 14 pM, respectively) and antiviral activity (IC50 = 5.3 nM and 2.0 nM, respectively). Inhibitor 5o also remained highly potent against a DRV-resistant HIV-1 variant.